Regulator device for a centrifugal blower



Oct 5 J. H. HOLLINGSWORTH ETAL 2,719,666

REGULATOR DEVICE FOR A CENTRIFUGAL BLOWER I Filed March 14, l

m M m m JOHN H. HOLL l/VGS WOR TH KARL L. BEDELL a F m APPROXIMATELY 2/3RAD/US 0F FAN APPROX/MA TEL r //2 x A ORNEY APPROX/MA TEL r M? x UnitedStates Patent Ofiice 2,719,666 Patented Oct. 4, 1955 REGULATOR DEVICEFOR A- CENTRJFUGAL BLOWER John H. Hollingsworth, Altadena, and Karl L.Bedell, Pasadena, Calif., assignors to Holly Manufacturing (Iompany,Pasadena, Calif., a corporation .ofCalifoi-nia Application March 14',-1952, Serial No. 276,645

4 Claims. (Cl. 230-414) This invention relates to improved dampers foruse in controlling the delivery of air ,or' other fluids from a blower.

Conventional dampers are located in the discharge duct adjacent to orsome distance down stream from the outlet of the blower. Dampers of thistype reduce the delivery of the blower by increasing the static pressureagainst which the blower must operate. Since large static pressures areproduced, such arrangements are inherently noisy and subject to leakagethrough any openings or joints in the duct system. Dampers of this typerequire a powerful operating mechanism because of the large staticpressures involved. Also, such' dampers deflect the air or other fluidwhich is discharged past the damper and this tends to createunequalpressures on any'branch ducts which are located immediately downstream from the damper.

These difficulties are overcome in our invention by providing a damperlocated in the housing of the blower which serves to change theefli'ciency of the blower, rather than to increase the static pressureagainst which the blower must operate.

Inaccordance with our invention, the damper islocated in the housing ofthe blower adjacent to the blades of the blower wheel so that the damperserves to cut the air or other fluid from the blower wheel. The damperalso serves to deflect the air or fluid into the'blades' of the blowerwheel so as to create turbulence within the scroll. This action servesto reduce the efficiency of the blower so that less pressure is createdwithin the blower and so that the delivery of the blowercan becontrolled by a damper which is considerably smaller than dampers whichare employed in conventional blowers. The location of the damper withinthe scroll of the blower can be varied within limits, but it must belocated adjacent the blades of the blower wheel.

Since our damper does not create large static pressures within theblower, it is not as noisy as conventional dampers. The force requiredto adjust the position of the damper is less than that required forconventional dampers, and consequently a smaller, lighter Weight andless powerful operating mechanism is required.

The invention is explained with reference to the drawings, in which:

Fig. 1 is an elevation of the outlet end of the blower; and

Fig. 2 is a sectional view along line 2-2 of Big, 1.

A conventional blower is shown in: the drawings; It comprises a scroll"housing with. a blower wheel 12 rotatably mounted in the housing. Theblades of the blower wheel ordinarily extend parallel to the axis ofrotation of the blower wheel. The housing has two inlet passageways 14and 16 for. air located around-the axis of rotation of the blower wheel,and an outlet passageway 18 for the air delivered by the blower. In someblowers only one inlet passageway is provided. Ordinarily a cutoff 20 isprovided on the scroll at a location intermediate the blower wheel andthe outlet passageway for causing the air which is carried by the bladesof the blower wheel to be delivered to the outlet passageway.

Our damper may be employed in various types of blowers, and it will beapparent that his not limited to use in the particular type blowerdescribed above.

The damper comprises a vane 22 of rectangular shape which extendsparallel to the axis of rotation of the blower wheel. The vane 22 issecured to a shaft 24 which is journaled in a pair of bearings 26, 28which are aflixed to the housing. A portion of the shaft 24 extendsoutside the scroll, and an arm 30 is affixed to this portion of theshaft for adjusting the position of the vane. The position of the arm 30may be adjusted by any suitable operating mechanism. It will be apparentthat the position of the shaft 24 may be adjusted in other manners whichare well known and will not be disclosed herein.

Preferably the vane22 is mounted off-center on the shaft 24. Since thevane 22 is located adjacent the blades of the blower wheel and thetransverse. dimension of the vane 22 extends different distances fromthe blower wheel, the forces exerted. by the fl'ow' of air against theportions of the vane 22 which are closest to the blower wheel aregreater than-the forces exerted against the portions of the vane 22which are farthest from the blower wheel. With the axis about which thevane 22 is rotatable offset toward the blower wheel from thelongitudinal axis of the vane as shown in the drawings, the forcesapplied by the flow off. air againstthe portions of the vane on eachside of the shaft are approximately balanced when the blower isoperating. With such an arrangement less force is'required tomove thevane than would be required if the vane were centered about the shaft'24.

The vane 22 is located adjacent the path of the blades of the blowerwheel and in the space between the blower wheel and the wall of. thehousing at the side of the outlet passageway which is opposite thecutoff 20 on the scroll. Since the vane 22 is employed to change theefficiency of the blower wheel, rather than being em ployed to increasethe static pressure against which'the blower must operate as inconventional dampers, the vane is considerably smaller than conventionaldampers. The area of the vane 22 is. less: than the cross-sectional areaof the outlet passageway 18, whereas" conventional dampers have an areawhich is equal to or larger than the outlet passageway so that the flowof fluid through the outlet passageway can be controlled by adjustingthe size of the opening between the damper and the outlet passageway.

Fig. 2 shows the damper substantially closed. In

' order to open thedamper, the'vane 22 is rotated approximately in aclockwise direction so that the transverse dimension of the vane extendsparallel to the direction of flow of air from the bladesof the blowerwheel toward the outlet passageway and the delivery of air from theblower wheel tothe outlet is not appreciably affected by the vane.

Stops 31A and 318150;; defining the-.limits-of movement of the vane maybe provided in the housing if desired. It will be apparent that thestops 31A and 31B may be omitted and that other typ of stops forlimiting the movement of the vane may-be provided. in the operatingmechanism if desired, Such stops may be of various conventional typesand arenot shown in the drawings.v

When the vane 22 is in a closed. or apartially closed position, it cutsair from the blower wheel and deflects the air into the blower wheel sothat the pressurized air is recirculated through the blades of theblower wheel. In effect, the vane serves as an adjustable cutoff for theair carried by the blower wheel.

When the vane 22 is in its closed position, the recirculation of aircauses some air to be forced out of the portions of the inlets which areadjacent the vane even thoughsome air is being drawn into the otherportions of the inlets.

The recirculation of air in the blower wheel causes turbulence whichreduces the efiiciency of the blower so that much smaller pressures aredeveloped within the blower than are developed by blowers havingconventional dampers which are located farther down stream.

Fig. 2 of the drawings show the relative dimensions and location of thedamper with respect to the blower wheel and the scroll of the blower ina preferred design. It has been found that these dimensions can bevaried somewhat without materially affecting the function of the damper.

Preferably, the axis about which the vane is rotated is spaced from theprojection of the axis of rotation of the blower wheel toward thesurface 32., a distance equal to approximately two-thirds the radius ofthe blower wheel, as shown in Fig. 2. However, it has been found thatconsiderable variation in this dimension is permissible and that thevane is effective if the axis about which it is rotatable is locatedwithin the space which is bounded by the projection of the axis ofrotation of the blower wheel and the projection of the outer peripheryof the blower wheel which is adjacent the outletv passageway, toward thesurface 32 of the scroll. are along planes which are disposed at rightangles with respect to the axis of the outlet passageway 18.

When the axis of rotation of the vane 22 is located as shown in Fig. 2,the width of the vane is preferably equal to approximately five-sixthsthe distance between the outer periphery of the blower wheel and thesurface 32.

It will be apparent that the dimensions shown in Fig. 2 are thosepreferred for a blower of a certain configuration and capacity, and thatthe preferred dimensions for other types of blowers would be somewhatdilferent. In order to employ the invention in other types of blowers,the dimensions should be arranged so that the damper vane is located inthe housing of the blower adjacent the outer periphery of the blades ofthe blower wheel and adjacent the outlet portion of the housing so thatthe damper vane may be employed to change the efliciency of the blower.

We claim:

1. In a blower for fluids comprising a scroll housing formed by aperipheral wall having opposite ends and a pair of oppositely disposedside walls, said housing having a central inlet and a horizontallyextending dis charge portion, said portion having a longitudinal axisand said portion terminating in a vertical plane, said horizontallyextending portion including one end of said peripheral wall, the otherend of said peripheral wall extending into the discharge portion forminga cutoff located inwardly of said vertical plane toward the axis of saidscroll housing, a blower wheel rotatably mounted in said housing havingan axis of rotation at right angles to said vertical plane, a dampervane having oppositely disposed edges, said damper vane having a shaftproviding an axis of rotation for said vane between said edges so that apart of said vane is located on both sides of said axis, said shaftextending in the same general direction as the axis of rotation of theblower wheel and mounted in said side walls for rotation in said scrollhousing, said axis of rotation of said damper vane shaft being adjacentsaid horizontally extending discharge portion and disposed in a space inthe housing, said space being bounded by a vertical plane from saidperipheral wall through the axis of the blower wheel, a second Theseprojections 1 vertical plane from the peripheral wall and tangential tothe outer periphery of the blower wheel, and said damper vane shaft axisbeing located in a third horizontal plane through said horizontallyextending discharge portion approximately midway between the peripheryof the blower wheel and the peripheral wall of the blower housing, oneside of said damper vane having a surface area of less than thecross-sectional area of the space between the periphery of the blowerand said peripheral wall of said housing taken on a vertical planethrough the axis of rotation of said damper vane.

2. In a blower for fluids having a scroll housing formed by a peripheralwall having opposite ends and a pair of oppositely disposed side walls,the housing having a central inlet and having a discharge portion whichineludes one end of said peripheral wall said discharge portion forminga discharge passageway, said passageway having a longitudinal axis, acutoff for fluids to be discharged located at the other end of saidperipheral wall, and a blower wheel rotatably mounted in the housing andhaving an axis of rotation which is disposed at right angles withrespect to the side walls of the housing, the improvement whichcomprises a damper vane having oppositely disposed edges, the dampervane having a shaft providing an axis of rotation for the vane betweensaid edges so that part of the vane is located on each side of the axis,the shaft extending in the same general direction as the axis ofrotation of the blower wheel and being rotatably mounted in the sidewalls of the housing, the axis of rotation of the damper vane shaftbeing located adjacent the discharge portion of the housing and beingdisposed in a space in the housing which is bounded by a first planepassing through the axis of rotation of the blower wheel and disposedperpendicularly with respect to the axis of the discharge passageway ofthe housing and by a second plane passing through the outer periphery ofthe blower wheel and disposed parallel with respect to the first plane,said damper vane shaft axis being located in a third plane disposed atright angles with respect to the other two planes and locatedapproximately midway between the outer periphery of the blower wheel andthe peripheral wall of the blower housing, and one side of the dampervane having a surface area which is less than the cross-sectional areaof the space between the outer periphery of the blower wheel and theperipheral wall of the housing along a fourth plane through the axis ofrotation of the damper vane and disposed parallel with respect to thefirst and second planes.

3. Apparatus according to claim 2 in which the axis of rotation of thedamper vane is asymmetrically disposed so that there is a largerproportion of the vane on one side of the axis than on the oppositeside.

4. Apparatus according to claim 2 in which the axis of rotation of thedamper vane is spaced from the plane passing through the axis ofrotation of the blower wheel perpendicular to the axis of the dischargepassageway a distance that is approximately two-thirds the radius of theblower wheel.

References Cited in the file of this patent UNITED STATES PATENTS783,267 Harris Feb. 21, 1905 826,869 Ortrnann July 24, 1906 1,787,653Anderson Jan. 6, 1931 2,014,507 Price Sept. 11, 1935 2,478,457 Camerinoet a1. Aug. 9, 1949 FOREIGN PATENTS 114,100 Germany Jan. 28, 1900556,746 Germany Aug. 13, 1932

